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Can't Connect to Internet - CM400 NetGear Modem Stuck at Blinking Upstream Light

Frequent Visitor

Can't Connect to Internet - CM400 NetGear Modem Stuck at Blinking Upstream Light

I already tried rebooting my modem and switching out coaxial cable. Also, ruled out wireless router issue. At this point I'm thinking its either the modem itself or an issue with the wiring behind the panel. 

 

Below is the info I was able to obtain for my modem.  Is this something I can adjust myself or will a tech have to come in?

 

Startup Procedure

Procedure

Status

Comment

Acquire Downstream Channel

543000000 Hz

Locked

Connectivity State

In Progress

Not Synchronized

Boot State

--

--

Configuration File

--

--

Security

Disabled

BPI+

IP Provisioning Mode

In Progress

Unknown

 

Downstream Bonded Channels

Channel

Lock Status

Modulation

Channel ID

Frequency

Power

SNR

Correctables

UnCorrectables

1

Locked

QAM 256

8

543000000 Hz

-19.1 dBmV

29.2 dB

91

533

2

Not Locked

N/A

N/A

0 Hz

0.0 dBmV

0.0 dB

0

0

3

Not Locked

N/A

N/A

0 Hz

0.0 dBmV

0.0 dB

0

0

4

Not Locked

N/A

N/A

0 Hz

0.0 dBmV

0.0 dB

0

0

5

Not Locked

N/A

N/A

0 Hz

0.0 dBmV

0.0 dB

0

0

6

Not Locked

N/A

N/A

0 Hz

0.0 dBmV

0.0 dB

0

0

7

Not Locked

N/A

N/A

0 Hz

0.0 dBmV

0.0 dB

0

0

8

Not Locked

N/A

N/A

0 Hz

0.0 dBmV

0.0 dB

0

0

 

Upstream Bonded Channels

Channel

Lock Status

US Channel Type

Channel ID

Symbol Rate

Frequency

Power

1

Not Locked

N/A

Unknown

0 Ksym/sec

0 Hz

57.0 dBmV

2

Not Locked

N/A

Unknown

0 Ksym/sec

0 Hz

57.0 dBmV

3

Not Locked

N/A

Unknown

0 Ksym/sec

0 Hz

57.0 dBmV

4

Not Locked

N/A

Unknown

0 Ksym/sec

0 Hz

57.0 dBmV

 

Event Log

      Clear Log              Refresh       

Time

Priority

Description

Time Not Established

Critical (3)

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out

Time Not Established

Critical (3)

No Ranging Response received - T3 time-out

Time Not Established

Critical (3)

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out

Time Not Established

Critical (3)

No Ranging Response received - T3 time-out

Time Not Established

Critical (3)

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out

Time Not Established

Critical (3)

No Ranging Response received - T3 time-out

Time Not Established

Critical (3)

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out

Time Not Established

Critical (3)

No Ranging Response received - T3 time-out

Time Not Established

Critical (3)

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out

Time Not Established

Critical (3)

No Ranging Response received - T3 time-out

Time Not Established

Critical (3)

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out

Time Not Established

Critical (3)

No Ranging Response received - T3 time-out

Time Not Established

Critical (3)

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out

Time Not Established

Critical (3)

No Ranging Response received - T3 time-out

 

Cable Information

 

 

Hardware Version

V2.0

 

Firmware Version

V2.01.02

 

Cable Modem Serial Number

**************

 

CM certificate

Installed

 

 

CM400 Basic.jpg

Diamond Problem Solver

Re: Can't Connect to Internet - CM400 NetGear Modem Stuck at Blinking Upstream Light

Has it ever worked or is it a new install? As of right now, your modem isn’t registering any upstream or downstream channels

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Frequent Visitor

Re: Can't Connect to Internet - CM400 NetGear Modem Stuck at Blinking Upstream Light

I tried a factory reset on my modem shortly after posting my OP.

 


@CCAndrew wrote:
Has it ever worked or is it a new install? As of right now, your modem isn’t registering any upstream or downstream channels

I've had this modem installed at my current address since December 2017.    I had a similier issue happen once before in 2018 at this adress but it seemed to have resolved itself after I switched out the coaxial cable.

Frequent Visitor

Re: Can't Connect to Internet - CM400 NetGear Modem Stuck at Blinking Upstream Light


@CaCunningham78 wrote:

I tried a factory reset on my modem shortly after posting my OP.

 


@CCAndrew wrote:
Has it ever worked or is it a new install? As of right now, your modem isn’t registering any upstream or downstream channels

I've had this modem installed at my current address since December 2017.    I had a similier issue happen once before in 2018 at this adress but it seemed to have resolved itself after I switched out the coaxial cable.


Clarification, that one time switching out the cable worked.  Didn't help this time around.

Expert

Re: Can't Connect to Internet - CM400 NetGear Modem Stuck at Blinking Upstream Light

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.



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Frequent Visitor

Re: Can't Connect to Internet - CM400 NetGear Modem Stuck at Blinking Upstream Light


@EG wrote:

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.


Hi EG:

 

I live in an apartment building with 5 other units.  As far as I know each unit only has one outlet and I don't have any splitters in mine.  There are two splitters in the basement with lines going to each of the 6 units. I managed to ask two of my other neighbors if their internet was working.  One just moved in so he didn't have his set up yet and the other's gateway had the internet light on so no issues on her end.  Don't know about the other 3units but it is definately not the line going into the building.   At this point I'm guessing its my modem or the line going directly into my unit.

 

I'm not about to go messing around with the wiring in a building I don't own so I have a tech coming in tomorrow so we'll see.

Expert

Re: Can't Connect to Internet - CM400 NetGear Modem Stuck at Blinking Upstream Light

Good luck with it ! Please post back with how things go.



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I am a Customer Expert volunteering my time to help other customers here in the Forums.
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Official Employee

Re: Can't Connect to Internet - CM400 NetGear Modem Stuck at Blinking Upstream Light

Hello CaCunningham78. We appreciate you visiting and posting on the Xfinity Forums. I can assist with further troubleshooting your internet connection issues. I'd like to start with polling the CMTS for real-time and historical RF signal reports from your modem. I can also check your local Node/Plant for any degradation or error reports. Please send me a private message and include your full name so I can access your equipment. Click my name (ComcastJoeTru) to view my profile, then click the link that says "Send a message". There you can private message me. 
 


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Official Employee

Re: Can't Connect to Internet - CM400 NetGear Modem Stuck at Blinking Upstream Light

Hi CaCunningham78. Since I didn't get a response from you, this thread has been locked. Please don't hesitate to send a private message if you continue to need help with this, or create a new post if you need assistance with anything else. Thank you.


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